Music notation has traditionally been written out by hand and entered in an automated system for publication as typeset or printed sheets. The manual process of handwriting, revising, and/or transcribing music notation can be very laborious for the music composer. For the music publisher, the conversion of handwritten notation into an automated typesetting or printing system requires the manual inputting of data, and only a limited capability exists for compositional modifications. The data generally must be reentered if the rhythm of the music is substantively changed.
Micro computers have been applied to music composition for digital processing of music data. Such computer systems allow a composer to compose on a keyboard and to store, manipulate, and output the data as synthesized music or as printed music notation. These systems have been generally of two types, i.e. realtime coding and non-realtime coding. In realtime coding systems, music is entered on an instrument keyboard, such as a piano-type keyboard, with exactly the timing and rhythm as it is intended to be played. The key inputs are analyzed by computer for their indicated pitches and the actual time durations and rhythms by which they are pressed on the keyboard in order to derive the proper notation. In non-realtime systems, the pitches are entered as separate data from their durations and rhythms.
As an example of a realtime system, Davis et al. U.S. Pat. No. 3,926,088 employs an organ keyboard on which an operator plays the pitch keys and a foot pedal which is pressed to indicate the start of each measure. The pitch keys in each measure are then processed into music notation according to the time durations and rhythmical ordering in which they are pressed. Such realtime systems have the disadvantage that the music must be played through with metronomic accuracy in order for the durations and ordering of the pitches to be analyzed correctly. The necessity of entering the pitch keys exactly as they are to be played severely limits the ability of the composer to compose or modify the music at the keyboard. Further, such systems have built-in limitations in discriminating notes of short durations or of complex rhythms.
In non-realtime systems, pitches are entered by selecting from an array of designated pitch keys, and the note durations associated with the pitches are entered separately by selecting from a prescribed set of binary fractions, i.e. halfs, quarters, eighths, sixteenths, etc., in order to define the desired music notes. Other rhythmical types, such as ties (continued notes) and rests (pauses), are entered in a similar manner as the pitches. For example, Rauchi U.S. Pat. No. 4,307,645 and Ejiri et al. U.S. Pat. No. 4,215,343 disclose non-realtime coding systems having keys for standard notes, ties, and rests in binary fractions. Namiki et al. U.S. Pat. No. 4,202,235 employs note duration keys in integer multiples of 1/16th intervals.
Such non-realtime systems are cumbersome to use since a specific duration is assigned in a fixed relationship to each pitch key. These systems have little capability of modifying the music notation into different time signatures without reentering the data. Moreover, the same rhythm representations in some cases may be played with different actual time durations, since conventional music notation uses binary note symbols whereas more complex rhythm structures may be desired. The assignment of a fixed binary symbol to each pitch in conventional systems would therefore result in music data that did not represent actual time durations for a wide range of rhythms, and would limit the usefulness of the data, for example, for playing the music on a synthesizer.